A SECOND major riot could soon break out at Strangeways prison - scene of the worst disturbances in British penal history - unless urgent action is taken to tackle inadequate staffing and growing unrest, chaplains at the Manchester jail said yesterday.

The warnings are made in a confidential letter to Robin Halward, governor of the prison, which has just been modernised at a cost of pounds 80m. The chaplaincy team complain about 'inadequate staffing levels' and 'intolerable burdens'.

Its letter says: 'The stress is beginning to tell . . . even now, with Manchester prison not yet filled to capacity, we are aware of the pressures building up on both staff and inmates and we are seriously concerned for what the future may hold.

'We would plead with those in authority to review once more the staffing levels in the prison, the job description, hours and working conditions of the staff, and to provide realistic out-of-cell activities for the prisoners. We urge this now so that we can avoid, for the second time in the history of Manchester prison, a situation when it becomes too late.'

Yesterday, the governor denied that there was any cause for concern and said there were a few 'teething problems'.

Two men died and 200 staff and prisoners were injured in the 25 days of rioting at the jail in April 1990. Five Victorian wings and a central rotunda were also destroyed. An inquiry by Lord Woolf recommended far-reaching changes in the way jails in England and Wales are run.

The Prison Service has promoted the refurbished jail as a model prison. Last week, it held an open day, the first since the jail began receiving prisoners again in April, attended by Peter Lloyd, the prisons minister. It currently holds about 700 inmates, mainly from the Manchester area, which will rise to more than 1,000 by the end of July. There are about 700 staff.

In the letter, the chaplains argue: 'The staff are being put under great pressure at the present time and achieve very little job satisfaction. The staff are expected to be all things to the men - jailer, counsellor, social worker and friend, and with the constant presence of prisoners out of cells with nothing to occupy their time, and what appears to us to be wholly inadequate staffing levels, they are under almost intolerable burdens.' These pressures have led to staff resigning, they say.

But Mr Halward denied Strangeways was on the verge of a new disturbance. 'There's an enormous commitment and hard work by the staff and it's producing a very satisfactory regime for the prisoners. There are teething problems, but there is an upside, which is a very much more relaxed environment which both staff and prisoners benefit from.'

John Bartell, chairman of the Prison Officers' Assocation, said that pressures to meet performance targets meant that standards had suffered and staff numbers had slumped to a dangerous level.

'The prisons are spiralling out of control and the Home Secretary, Michael Howard's, new Criminal Justice Bill has nothing to address the imminent prison crisis,' he said. 'The fact that Manchester was the scene of the worst prison riot we have witnessed in this country should be a salutary warning to Mr Howard.'